Thomas Forster: WQOs and BQOs

Abstract: A WQO is a transitive reflexive relation with no infinite antichains and no infinite strictly descending chains. In this introductory talk (very few proofs!) for a general mathematical audience i shall try to show some of the many places that WQOs have spread their tentacles into, how they give rise to BQOs, the connections with finite combinatorics (Seymour-Robertson theorem), undecidability results in arithmetic and other fun stuff. I’ll even tell you what the two TLAs stand for.